Transformer.



W. S. MOODYx TRANSFORMER.

APPLIOMION HLED DB0.16,1S01,

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. PATENTED JAN.1, 1907. W. S. MOODY.

TRA BTS-FORMER.

APPLICATION FILED DEU.16.1901.

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UNITED sra'rnsgra'rsu'r enrich.

WALTER S. MOODY, 0l .SCHENEGTADY, NEW YORK,` SSIGNOR T() GEN- FiAL ELECTR' OMPANY, A CORPORATION OF NEW YORK.

TRANSFORMER..

Specicaton of Letters Patent.

Patented Jan. 1, 1907.

Application lled December 16, 190].. Serial No. 86.030.

windings adapted for interchangeables con-V nection on different-supplied voltages, and to facilitate the mechanical construction of the transformer:

A serious difficulty which is always encountered in transformers of this class when they are required to supply more than one voltage, and especially when used in'connection with three-wire circuits, is that of ob? taining automatic regulation. The simplest transformer of this class has its two windings subdivided, the resulting parts being mountedbnlthe respectivecore-legs, so that half of each winding is located on each leg. N hen from between the two parts of the secondary winding of such a transformer a connection is taken tothe neutral of a threefvvire system, the loads on the sides of which are frequently varied with respect to each other, it happens tliat the voltage of the more heavily loaded part of the secondary decreases, while the voltage of the less heavily loaded part increases, this condition being the reverse of that desired. This result is due to the fact Athat the increased secondary ampere-turns caused by overloading cppose in an mcreased degree the ampere-turns of the part of the primary on the same leg of the core, so that there is established an opposition to the magnetization of the other core-leg. This opposition of magneto-motive forces causes the establishment of colisequent poles inthe end pieces of the core which connect the corelegs to complete the' magnetic circuit, and a part of the flux which Aought to pass through the leg carrying the more heavily loaded secondary is shunted as leakage from pole to pole across the air-space between the legs. This occurs in a very high degree when, as is customary, the transformer is incased in an iron boX, which of course provides a ready path for the leakage iux. Therefore since the core-leg on'which the more heavily-load ed..secondary is mounted carries a smaller flux than the other leg the secondary coils on the former leg have a smallerinduced voltage per turn than the coils on the latter leg, and the counter-electromotive force of the part of the primary onthe more heavily loaded side will therefore be reduced. It should be ynoted at this point that no flux is shunted from the core on which the lightly-loaded secondarv is mounted. Now it is clear that the generator will supply more current when the voltage of the primary on the .loaded side drops, with the result that the whole core magnetization is increased,which causes/in# creased voltage on the primary and secondary on the unloaded side of the system. Since the sum of the voltages on the twoparts of the primary must be substantially equal to the impressed voltage, which is constant, 'it follows that all the coils on the loaded leg of the core have less `than the normal voltage,

while those on the unloaded 'leghave a voltage higher than the normal, which is the reverse of the required conditions, as abovestated.

` ln Patent N o. 595,403, issued to me on December 14, 189,7, is disclosed an arrangement of the secondary coils whereby the above-described difficulty is overcome by subdividing thc part of thc secondary on each leg into two parts and connecting parts of the secondary on both core-legs across the respective sides of the three-wire system. The present invention is another embodiment of the same generic idea-namely, that no matter how much more heavily loaded one side of the three-wire system may be with this arrangement of secondary coils the total.demagnetizing effect of the secondary coils will always act e ually on each leg of the core and there wil be no tendency to unbalance the flux. The specific .disclosure in said atent shows the secondary divided into 'our parts instead of two, as before, and each part on one core-leg is connected in series with a part on the other core-leg, tlc pairs being connected across the respective sides of the three-wire system. l have ft und that the parts of the secondary coils of the ,different IOO legs can be connected in multi le across one sideof a three-wire system wit out interfer- .ingwith the good automatic regulation obtained b`y connecting two coils on dierent legs across one side'of the system,` as shown in my patent above noted. By thus connecting the coils in multiple an im ortant advan-l tage is gained in that the co1 s on the' same core-leg or lon different core-legs canl be changed from a series connection to vary vthe ,potential either on a three-wire circuit or on a two-Wire circuit of double volta e.

Of the drawin s, Figure 1 is an e ovation of a transformer o the core type, showing the primary and secondary windings 'mounted onf th two parallel core-legs. Fig. 2v is a plan of the same, showing the concentric. arrange- .ment of the primary and secondary coils and vthe connections of the primary. Fig. 3 is an elevation of the same transformer, showing the. primary "coils in dotted lines to disclose the secondarycoils;` F1g. 4 is-a plan of the same,show`ing 'the lconnections of the secondairy Winding entering' the lvconnectionboard B'.l Fig'. 5 is 'a partial 'view of the trans- ,p 'former casing, s'lnN/'ing fthe secondary connections of Fig; 4 extending out of the casing.

Figiis an 'elevation'ofthe single-circuit core Without'the primary Winding and showing in seetionfthe'inner and outer coils -IS and OS of secondary. mounted 4on the parallel' core-,lega the two parts of the windin .-zon 'the same leg being connected in mul tip' e` with `each other for the lowest voltage. l Fig. Tis an elevation jof the transformer withoutl the primary winding, showing the out- Yside secondary woundwith ta e T, the coils 'being connected in series for t eA next higher voltage. Fig. 8 is a view iin) which the coils constituting a pair or set, one on one le and one on the other, are connected in mu across one side of a three-wire circuit.

9 isla partial view of a` transformer-casing, showing the secondary leads emerging from the casing, as inFigs. 4 and 5, and/connected,

f as iii Fig. 8. Fig. 10 is a partial viewof the casing/showingl secondaryl leads emergin from the .casin which leads are oonnecte in a slightly-di erent manner from Fig. 8 to obtain a `multiple connection of the coils on the different legs; and Figs. 1 1 and 12 are diagrams showing the connections of the leads in Figs. 9 andy 10, respectively, to the secondaries of the transformers.

.,Itl is preferable, although not necessary, that; lthe primary should be mounted outside the secondary, as shown in Figs. 1

andf2, in order to obviate .the necessityof vinsulating both sides of the high-potential wmding from the 'other' winding and from the fcore. It is highly desirable also in this typtJ of transformer that the high. and low potential windings should `Vbe mounted concentrically with' respect toI each other,` as

escaso shown in Figs. 2 and =3. The primary winding may be composed, as shown, of a number of separately-wound coils I), connected in series. 'The windings are usually mounted orithe legs of the core Oin the positions arrangement; but the invention is not limited lto this, 'as-the coils may be mounted in other ways. The 'core is preferably constructed with a cruciform cross-section, as indicated in Figs.V 2 and Li, and is preferably built up of steel sheets in any manner suitable for completing the magnetic circuit. The leads Pa PX of the separate primary coils connected in series on one leg and the leads Pb PY of the separate primary coils connected in series on the other leg are suitably arranged, as shown in Figs. 1 and 2, so that all the coils on one leg can" be connected in series or multiple with the coils on the other leg t9 adapt them to diHerent impressed voltages. I have found that this variation of the series and multiple relations of these sets of coils does not affect the automatic regulation attained as a result of the arrangement of the secondary coils inaccordance with the present invention, as in any event in case one side of the three-wire system is more heavily loaded than the other the disposition of the loaded secondary on both legs of the core prevents any opposition of magnetizing forces, which poles and a shunt iiuX of leakage.

As shown in Figs. 2 and 4, the secondary winding Sis divided into four coils, two of which' are mounted onleach core-leg, the

coils IS an'd all of them extending the entire length of the core-legs. As shown in Fig. 3, the leads of all the .coils are brought up to the topof the'apparatus. In this figure S3 and S4 are the start and finish of the left-hand inner coil IS, S and S2 are the start and finish of the left-hand outer coil OS, S5 and S6 outer coil OS, and S7 S8 are the start and finish of the right-hand inner coil IS. As shown in Fig. 4, these leadsare carried through a connection-board B so 'as tobe brought out of the transformer-casing O of Fig. 5 in the order indicated inthe latter figure.

In Figs. Sand 8 the primary winding is the secondary coils may be more readily understood. In Fig. 6 the four coils of the secondary winding are shownin section, being separated from the core O by the insulation I', from each other by the insulation I2, and from the 'primary coils by insulation which is composed in part of the tape T of Fi 7.

n. important mechanic'l advantage in providi two secondary coils in multiple on each leg 1s the opportunity it' oersof windvshown. -4'l`his has been found to be the best .not shown -in order that the arrangement of would result in the formation of consequent IOO outer coils OS being'concentric with the inner ros are the start and finish of the right-hand IIC 'equivalent of that shown in Fig. 8.

ing a transformer for a very large current output without using heavy conductors, the

objection yto heavy conductors being ot course the diiiculty of bending them into coils of small diameter. The multiple coils can carry heavy loads which a single coil could not, unless it were so heavy that the core would be twisted in the process oi' winding conductors upon it. The conductors are usually wound in a sheet of four wires, so that it the wires are very large the core is subjectedV to great strains in winding. An' important electrical result in providing two secondary coils on each leg is that the transformer can supply current of three different voltages. ln Fig. 6 the two coils on each leg are connected in multiple with each other to supply,l for example, one hundred and i'iiteen volts. ln Fig. 7 the coils on one leg are in multiple with each other, and each is in series with one of the coils on the other leg to supply twice said voltage or two hundred and thirty volts. The most imprrtant result to be obtained .by the use of the invention, however, is shown in Fig. 8, vhere one coil on one leg is in multiple with a coil on the other leg across one side of a three-wire system and the other coil on the irst leg is in multiple with the other coil on the second .leg across the other side of the three-wire system. The set of coils having the leads' S S2 and S7 S8 is connected across one branch of the three-wire circuit, andthe set of coils having the leads S3 S4 and S5 S is connected across the other branch of the three-wire circuit, the coils`oi each of these sets being connected in multiple, one in each set being located on one leg of the core and the other of said set being located on the other leg of the core.

ln Figs. Qand 11 is shown the method oi connecting the leads extending outside the casing, as shown in Fig. 5, in accordance with the arrangement shown in Fig. S. Leads S4, S6, S2, and SB, which are the iinisliing-leads of the respective Jfour coils, are all connected with the neutral N. The starting-lead S3 of the left-hand inside coil and the starting-lead of the right-hand outside coil are both connected to one outside line of the three-wire circuit, and the startinglead S of the left-hand outside coil and the starting-lead S7 ot the lett-hand inside coil are both connected to the other outside line of the three-wire circuit. It is thus ,clear that a coil on each leg in multiple with a coil on the other leg is connected across one and the other side ot' the system respectively,

. ln Figs. 10 and l2 is shown a manner of connecting parts of. the secondary on difterent legs in multipleacross one side ot a threewire system, which manner is the electrical This arrangement possesses the mechanical and economical advantage, however, that the secondary is composed ot only two coils, one on each leg. Leads A and B extend from intermediate points of these two coils and are connected by the lead L2 with thc neutral N ot a three-wire system. The leads Aand B of the two coils are connected by the lead L to the line W oi the three-wire system, and the leads A2 and B2 of the two coils are connected by the lead lfto the line W2 of the three-wire system. By these connections a part ot the coil on one leg is connected in multiple with apart ot the coil on the other leg across one side ofthe three-wjre circuit, and the other part of the coil on the irst leg is connected in multiple with the other part of the coil on the other leg across the other side of the three-iv ire circuit. Thus the demagnetizing el'lect of a more heavily loaded secondary will act equally' on both core-legs or along the entire length of the core even though four separate coils are not provided, in Fig. 8. lt is preferable, however, that each of these secondary coils be wound throughout its length with a dou-ble conductor in order that all parts may be in proximity to the coils olI the primary, which would not be the case il` eaclfi secondary coil were wound v ith a single conductor and the leads A or B were tapped mid way into it. When each secondary coil is thus wound with two' conductors the arrangement is practically thex same as that shown in F ig. 8, the only diilicrence being that in the former case, as in 'Fig'. 10, the part ot' the winding on one leg is composed of a continuous conductor and is a single mechanical structure.

.lhat l claim as new, and desire to secure by Letters Patent ol' the Unit ed States, is

n l. ln a transformer, the combination with a core constituting a single magnetic circuit, of a winding'consisting ol sets of coils, the sets being located on dill'crent parts of the core, the coils on the same part, of the core being connect ed respectively in series with coils on another part ol the coro and the sets of coils in series being joined in multiple, and a second winding ininductive relation with respect to the iirst winding.

2. In a transformer, the combination with a core constitul ing a single magnetic circuit, of a winding consisting of multiply-connect ed sets of coils, each set. consisting ot au inner and an outer coil in series with cach other.

3. The combination in a transformer, of a 4. In a transformer, the combination Witlny In Witness Whel-'eof I have hereunto set my a Core constituting e single magnetic circuit, I hand this 11th day of December, 1901, of a Winding consisting of I1111tp1y-connect I ed seti.:l of coils located on different parts of WALTER S MOODY 5 the core, each set consisting ofvanuinne'r coil Witnesses;

onv one part of the core in series with an BENJAMIN B. HULL,

outer coil on another part of the core. l MARGARET EL WooLLEY. 

